Self-extinguishing polyolefin compositions



3,474,067 SELF-EXTWGUISIHNG POLYOLEFIN COMPOSITIONS Hans Eberhard lPraetzel, Bensberg-Frankenforst, and

Herbert Ilenkner, Cologne-Deutz, Germany, assignors to Chemische Fabrik Kalk G.m.b.H., Cologne-Kalli, Germany No Drawing. Filed Feb. 10, 1966, Ser. No. 526,365

Claims priority, application Germany, Feb. 18, 1965,

C 35,123; Get. 15, 1965, C 37,172 Int. Cl. (108i 29/12, 45/56; C09 3/28 Cl. 260-41 10 Claims ABSTRAiI'li F rem DHSCLOSURE Self-extinguishing polyolefin based compositions containing 1 to 20 wt. percent of at least one nuclear halogenated polystyrene selected from the group consisting of poly-(monobromostyrene), poly-(dibromostyrene), poly- (tribromostyrene), poly (tetrabromostyrene), poly- (monochlorodibromostyrene), poly (dichloromonobromostyrene) and poly-(monochloromonobromostyrene) and from 1 to 10 wt. percent of antimony compound and if desired also containing another organic chlorine compound providing /2 to 5 wt. percent of chlorine in such compositions.

This invention concerns polyolefin-based self-extinguishing moulding materials.

By reason of their favourable physical properties, polyolefin-based moulding materials may be used for the most widely diverse industrial applications, particularly as insulating material in the electrical industry. However, the ready combustibility of such moulding materials considerably restricts their possible applications. The combustibility of polyolefin-based moulding materials can be reduced by the addition of flameproofing components such as chloroparafiins, chloronaphthalene or hexachlorocyclopentadiene and synergistic substances such as antimony trioxide. Since, however, considerable quantities of chlorine compounds and antimony trioxides have to be added for this purpose, the mechanical and physical properties, particularly the tensile strength, of polyolefin-based moulding materials are considerably lessened.

It is known that polyolefin-based moulding materials can also be rendered less inflammable by the addition of organic bromine compounds such as for example tribromo-aniline, pentabromodiphenyl ether and other lowmolecular aromatic bromine compounds. It has however proved that; smaller quantities of organic bromine compounds than of chlorine compounds have to be added to the moulding materials in order to achieve the same flameproofing effect. Therefore, the disadvantageous influence on the mechanical and physical properties of the moulding materials is correspondingly less if organic bromine compounds are added. By virtue of their lower molecular weight, these organic bromine compounds migrate out of the moulding materials again unless the flameproofing component is absolutely compatible with the polyolefin. In many cases, the migration results in an adhesive film forming on the surface of the polyolefins. It

nited States Patent 0 3,474,%7 Patented Oct. 21, 1969 ice is true that the surface of the polyolefin can be cleaned again by being wiped, but this film continues to form afresh because the flameproofing component is being constantly supplied from within. This process means that the interior of the moulding material slowly grows poor in the flameproofing component. With increased reduction in the content of fiameproofing component, however, the combustibility of the moulding material increases once again.

Polyolefin-based moulding materials were therefore sought which were self-extinguishing and which did not exhibit the disadvantages of the known self-extinguishing polyolefin-based moulding materials.

Self-extinguishing polyolefin-based moulding materials were found which contained organic bromine compounds and possibly organic chlorine compounds as flameproofing components and antimony compounds such as antimony trioxide and antimony oxychloride as synergistic substances. It is characteristic of these moulding materials that they contain, as organic bromide compound, 1 to 20% by weight and preferably 3 to 15% by weight of nuclear halogenated polystyrenes from the group consisting of poly- (rnonobromostyrene), poly (dibromostyrene), poly-(ribromostyrene), poly-(tetrabromostyrene), poly-(monochlorodibromostyrene), poly (dichloromonobromostyrene), poly-(monochloromonobromostyrene) and mixtures thereof, and 1 to 10% by weight and preferably 3 /2 to 5% by weight antimony compounds.

As polyolefins, the moulding materials according to the invention may contain high or low-pressure polyethylene, polypropylene, polybutylene, polyisobutylene or polybutadiene or copolymers thereof.

The nuclear-halogenated polystyrene present in the moulding materials according to the invention is obtained by the polymerisation of appropriate nuclear-halogenated styrenes as finely distributed solids. The nuclear-halo genated polystyrenes are added to the polyolefin-based moulding materials in such quantities that these latter preferably contain about 4 to 6% by weight aromaticallybonded bromine and 0 to 20% by weight aromaticallybonded chlorine. In addition to the nuclear-halogenated polystyrenes and the antimony compounds such as for example antimony trioxide and antimony oxychloride, which are known as synergistic compounds, the polyolefinbased moulding materials can also contain /2 to 5% by Weight chlorine in the form of organic aliphatically bonded chlorine compounds. Suitable chlorine compounds of this kind are for example chloroparaffins with a chlorine content of 45 to 72% by weight, dimerised hexachlorocyclopentadiene, polyvinyl chloride, post-chlorinated polyvinyl chloride and chlorinated polybutadiene.

Since the halogen is split off from the aliphaticallybonded chlorine compounds at a lower temperature than from nuclear halogenate polystyrenes, an additional flameproofing is achieved in this way for low-temperature and smouldering fires. In these cases, the content of nuclear-halogenated polystyrenes in the moulding materials can be restricted to 1 to 8% by weight.

The nuclear-halogenated polystyrene is admixed with the p'olyolefin-based moulding material in powdered form, together with the antimony compound and, if applicable, the organic chlorine compounds, before or during plasticisation, and worked in per se known manner, for example by means of an extruder or a mixing mill.

The nuclear-halogenated polystyrenes and the antimony compounds present in the moulding materials composed according to the invention are similar to a filler. As a high-molecular compound, the nuclear-halogenated polystyrene has a reduced tendency to migrate.

polystyrene selected from the group consisting or poly (monobromostyrene), p'oly-(dibromostyrene poly (tribromostyrene), poly-(tetrabromostyrene t. poly (monochlorodibronrostyrene), poly (dichlo- -romonobromostyrene) and poly-(monochloromon'o- Some examples of moulded articles composed accordbromostyrene) and m1xtures thereof, and ing to the invention are given hereinafter. These examples (0) from 1 to by weight of an antimony comdo not imply any limitation of the method and products pound selected from the group consiting of antimony according to the invention. trioxide and antimony oxychloride.

In the case of polypropylene and high or medium-pres- IO 2. A composition according to claim 1 which COlllsure polyethylene, the granulate involved is plasticised prises 3.5 to 5% of antimony trioxide. at temperatures of 190 or 130 or 160 C. respectively and 3. A composition according to claim 2 in which the the mixture of flameproofing components worked in under nuclear-halogenated polystyrene is nuolearly brominated the conditions set out in the following tables, under roller poly-(tribromostyrene). skin friction. Homogeneous distribution of the fiame- 4. A self-extinguishing moulding composition consistproofing components is achieved in that the roller skin is ing essentially of removed from the roller and turned several times. The (a) a polyolefin, finished roller skin is reduced to granular form from (b) from 1 to 8% by weight of a nuclear-halogenated which the desired moulding is produced in the plasticised polystyrene selected from the group consisting of state, poly (monobromostyrene), poly-(dibromostyrene Low-pressure polyethylene powder is blended with the poly (tribromostyrene), poly-(tetrabromostyrenet, flameproofing components in a conventional mixer. The poly (monochlorodibromostyrene), poly (dichlomixture obtained is extruded at a temperature of 190 C. Tomonobromostyrene) and poly-(monochloromonoto form the desired moulded articles. brom-ostyrene) and mixtures thereof,

The behaviour of the samples produced under condi- (c) from 0.5 to 5% by weight chlorine in the form of ti-ons of fire is tested according to ASTM Specification an organic aliphatically-bonded chlorine compound No. 635. selected from the group consisting of solid chloro- According to this specification, test bars measuring 13 X parafiins with a chlorine content of 45 to 72% by 6.5 X 127 mm. are cut from the moulded articles to be weight, dimerised hexachlorocyclopentadiene and tested. These test bars are clamped horizontally at one polyvinyl chloride, and end in a clamping stand in such a way that the narrow side (d) from 3.5 to 5% by weight of an antimony com of the largest of the lateral faces forms an angle of 45 pound selected from the group consisting of antimony to the horizontal. Under the sample and about 9.6 mm. trioxide and antimony oxychloride. from it, there is a large Bunsen burner wire gauze about 5. A composition according to claim 4 wherein the 10.3 sq. cm. in size with 58 meshes/ sq. cm. and 116 mm. polyolefin is polyethylene. in length, likewise held by a clamp. For the fire test, a 6. A composition according to claim 4 wherein the non-luminous Bunsen burner flame is applied to the free polyolefin is polypropylene. end of the test bar for 30 seconds and the time required for 7. A composition according to claim 4 wherein said the sample to extinguish itself after removal of the flame is nuclear-halogenated polystyrene is poly-(tribromostymeasured. rene).

TABLE 1 Poly-(tribromostyrene), SbzO Parts by parts by parts by Aliphatieally-bonded chlorine compound, Extinguishing Number weight Polyolefin Weight Weight parts by weight time 150 High-pressure polyethylene 9. 7 5. 8 2.7 solid chloroparafiin Cl) Less than 1 sec.

(Density 0.918). 150 Medium-pressure polyethylene 9.7 5.8 2.7 dimerised hexachlorocyclopentadiene Do.

(Density 0.925). 150 Low-pressure polyethylene 9.7 5.8 do Do.

(Density 0.948). 150 Polypropylene 9.7 5.8 do Do. 150 Low-pressure polyethylene 9. 7 5. 8 2.7 post-chlorinated PVC (70% Cl) and 0.3 Do.

(Density 0.948). stabiliser. 150 do 9.7 5.8 2.7 solid chloroparafiin (70% Cl) Do. 150 Medium-pressure polyethylene 9.7 5.8 do Do.

(Density 0.925).

TABLE 2 SbzO Extinguishing Nuclear-halogenated parts by Aliphatically-bonded chlorine time per Number Polyolefin, parts by weight polystyrene, parts by weight weight compound, parts by Weight ASTM 635 1 100 low-pressure polyethylene 5.7 poly-(tetrabromostyrene) 3. 1.8 solid chloroparatfin (70% by Less than 1 sec.

(Density 0.948). weight Cl). 2 medium-pressure polyethylene 7.1 poly-(dibromostyrene) 3. 85 1.8 dimerised hexachlorocyclo- Do.

(Density 0.925). pentadiene. 3 100 high-pressure polyethylene 10.0 poly-(monobromostyrene) 3.85 1.8 solid chloroparafiin (70% by D0.

(Density 0.918). I Weight Cl). 4 100 polypropylene 11. poly-gmonochlorodibromo- 3. 85 do D0.

5 yrene 5 do 14.2 p ly-(dichl0r0m0nobr0mo 3.85 1.8 dimerised hexaehlorocyclo- Do.

styrene) pentadiene.

We claim: 8. A composition according to claim 4 wherein said A self'extmgmshmg mouldmg Composmon aliphatically-bonded chlorine compound is a solid chloroprising (a) a polyolefin, (b) from 1 to 15% by weight of a nuclear-halogenated parafiin.

9. A composition according to claim 4 wherein said References Cited UNITED STATES PATENTS 2,480,298 8/1949 Happoldt 260-285 3,063,954 11/1962 Galizia 260-25 10 3,121,067 2/1964 Nelson 26041 6 OTHER REFERENCES Miles at 21., Polymer Technology, Temple Press Books,

London, 1965, pages 342-344.

Marvel et al., Polystyrene and Some of its Derivatives,

5 in American Chemical Society Journal, vol. 62, 1940,

pages 45-49. MORRIS LIEBMAN, Primary Examiner J. H. DERRINGTON, Assistant Examiner US. Cl. X.R. 260-45.75, 897 

